Bottoming The Suspension Out Hard!
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From: Detroit
Some preliminary results from a cheap experiment: It’s not that I’m obsessed with being cheap, but the engineer part of me is attracted to a basic engineering axiom known as the KISS principle. It stands for, "Keep it simple, stupid!"
What would be one of the simplest and most cost-effective ways to get progressive springing? A larger and cushier bumpstop. The more the rubber is compressed, the more resistance it has to being compressed further.
So I glued some pieces of innertube rubber together, making a pad about 1” by 1”, and a little under ˝ inch thick. and stuck it to the factory bumpstop with doublesided tape. Why innertube rubber? Because it is easily available, it’s easy to vary the thickness experimentally by adding or subtracting layers, and because innertube rubber has fairly uniform and repeatable properties, or “squishiness”.
Testing it two-up, the home-made rubber nerd compressed all the way on the largest bumps, still allowing the swingarm to reach the end of its travel on occasion, but the hit wasn’t nearly as hard. In fact, we didn’t really feel the bottoming out as we had before . The only way I knew it had happened was because I put some modeling clay on the factory part of the bumpstop, and it was squashed flat.
The height and width of the additional bumpstop might need to be refined a bit to get things optimal, but this could be a useful idea for those with lowered bikes, which have less suspension travel. My Rocker isn’t lowered, but it comes from the factory with about an inch less rear suspension travel than most softails. So does the Fat Boy Low, and maybe a few other bikes. This method keeps the suspension normal and comfortable for most riding, but adds stiffness when it gets about 2/3rds of the way to bottoming out.
Below is a photo showing the original factory bumpstop, with the extra nerd stuck at the center. At the left is the squashed yellow clay, showing that the swingarm still traveled all the way to the factory bumpstop. Sorry about the bike being so filthy. It had just been ridden home in the rain from a Memorial Day run/rally/ceremony.
What would be one of the simplest and most cost-effective ways to get progressive springing? A larger and cushier bumpstop. The more the rubber is compressed, the more resistance it has to being compressed further.
So I glued some pieces of innertube rubber together, making a pad about 1” by 1”, and a little under ˝ inch thick. and stuck it to the factory bumpstop with doublesided tape. Why innertube rubber? Because it is easily available, it’s easy to vary the thickness experimentally by adding or subtracting layers, and because innertube rubber has fairly uniform and repeatable properties, or “squishiness”.
Testing it two-up, the home-made rubber nerd compressed all the way on the largest bumps, still allowing the swingarm to reach the end of its travel on occasion, but the hit wasn’t nearly as hard. In fact, we didn’t really feel the bottoming out as we had before . The only way I knew it had happened was because I put some modeling clay on the factory part of the bumpstop, and it was squashed flat.
The height and width of the additional bumpstop might need to be refined a bit to get things optimal, but this could be a useful idea for those with lowered bikes, which have less suspension travel. My Rocker isn’t lowered, but it comes from the factory with about an inch less rear suspension travel than most softails. So does the Fat Boy Low, and maybe a few other bikes. This method keeps the suspension normal and comfortable for most riding, but adds stiffness when it gets about 2/3rds of the way to bottoming out.
Below is a photo showing the original factory bumpstop, with the extra nerd stuck at the center. At the left is the squashed yellow clay, showing that the swingarm still traveled all the way to the factory bumpstop. Sorry about the bike being so filthy. It had just been ridden home in the rain from a Memorial Day run/rally/ceremony.
Last edited by Warp Factor; May 29, 2013 at 10:44 AM.
Outstanding HDF Member
Joined: Jun 2007
Posts: 2,796
Likes: 36
From: Toronto, Ontario
you sir are awesome 
and got me thinking .. too 
Some preliminary results from a cheap experiment: Its not that Im obsessed with being cheap, but the engineer part of me is attracted to a basic engineering axiom known as the KISS principle. It stands for, "Keep it simple, stupid!"
What would be one of the simplest and most cost-effective ways to get progressive springing? A larger and cushier bumpstop. The more the rubber is compressed, the more resistance it has to being compressed further.
So I glued some pieces of innertube rubber together, making a pad about 1 by 1, and a little under ˝ inch thick. and stuck it to the factory bumpstop with doublesided tape. Why innertube rubber? Because it is easily available, its easy to vary the thickness experimentally by adding or subtracting layers, and because innertube rubber has fairly uniform and repeatable properties, or squishiness.
Testing it two-up, the home-made rubber nerd compressed all the way on the largest bumps, still allowing the swingarm to reach the end of its travel on occasion, but the hit wasnt nearly as hard. In fact, we didnt really feel the bottoming out as we had before . The only way I knew it had happened was because I put some modeling clay on the factory part of the bumpstop, and it was squashed flat.
The height and width of the additional bumpstop might need to be refined a bit to get things optimal, but this could be a useful idea for those with lowered bikes, which have less suspension travel. My Rocker isnt lowered, but it comes from the factory with about an inch less rear suspension travel than most softails. So does the Fat Boy Low, and maybe a few other bikes. This method keeps the suspension normal and comfortable for most riding, but adds stiffness when it gets about 2/3rds of the way to bottoming out.
Below is a photo showing the original factory bumpstop, with the extra nerd stuck at the center. At the left is the squashed yellow clay, showing that the swingarm still traveled all the way to the factory bumpstop. Sorry about the bike being so filthy. It had just been ridden home in the rain from a Memorial Day run/rally/ceremony.
What would be one of the simplest and most cost-effective ways to get progressive springing? A larger and cushier bumpstop. The more the rubber is compressed, the more resistance it has to being compressed further.
So I glued some pieces of innertube rubber together, making a pad about 1 by 1, and a little under ˝ inch thick. and stuck it to the factory bumpstop with doublesided tape. Why innertube rubber? Because it is easily available, its easy to vary the thickness experimentally by adding or subtracting layers, and because innertube rubber has fairly uniform and repeatable properties, or squishiness.
Testing it two-up, the home-made rubber nerd compressed all the way on the largest bumps, still allowing the swingarm to reach the end of its travel on occasion, but the hit wasnt nearly as hard. In fact, we didnt really feel the bottoming out as we had before . The only way I knew it had happened was because I put some modeling clay on the factory part of the bumpstop, and it was squashed flat.
The height and width of the additional bumpstop might need to be refined a bit to get things optimal, but this could be a useful idea for those with lowered bikes, which have less suspension travel. My Rocker isnt lowered, but it comes from the factory with about an inch less rear suspension travel than most softails. So does the Fat Boy Low, and maybe a few other bikes. This method keeps the suspension normal and comfortable for most riding, but adds stiffness when it gets about 2/3rds of the way to bottoming out.
Below is a photo showing the original factory bumpstop, with the extra nerd stuck at the center. At the left is the squashed yellow clay, showing that the swingarm still traveled all the way to the factory bumpstop. Sorry about the bike being so filthy. It had just been ridden home in the rain from a Memorial Day run/rally/ceremony.
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